Investigation of the mechanism of acceleration of fatigue crack initiation based on modelling the hydrogen using HELP model

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K14151
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Aoyama Gakuin University
• Principal Investigator: Shota Hasunuma 青山学院大学, 理工学部, 准教授 (50709764)
• Project Period (FY): 2022-04-01 – 2024-03-31
• Keywords: 水素 / 疲労 / き裂発生 / 転位

Outline of Final Research Achievements

In this study, the effect of hydrogen on fatigue crack initiation of aluminum was investigated based on HELP(Hydrogen Enhanced Localized Plasticity)model. Two types of simulations were performed in this study. First, 2-dimentional fatigue crack initiation simulation was performed. Two mechanisms of HELP were modeled: reduction of the dislocation interaction stress and an increase of the dislocation velocity by hydrogen. Simulations of the crack initiation were performed by discrete dislocation dynamics with the HELP model. The simulation results indicated that HELP accelerates fatigue crack initiation. Second, 3-dimentional tensile simulation was performed. Increase of the dislocation velocity by hydrogen was modeled and this model was introduced into dislocation dynamics. The simulation results indicated that 0.2 % proof stress was decreased with increasing the hydrogen. However, the decreasing of 0.2 % proof stress was saturated.

Free Research Field

材料強度

Academic Significance and Societal Importance of the Research Achievements

再生可能エネルギーの活用のために，燃料電池自動車や風力発電などに注目が集まっている．これらの機器において問題になるのは，超高サイクル疲労強度に及ぼす水素の影響である．水素により疲労き裂発生寿命は低下するが，そのメカニズムは解明されていない．本研究では，HELP機構，特に水素による転位の易動度の増加により疲労亀裂発生が加速することが明らかとなった．また，水素の影響を導入した三次元転位動力学法により，水素による降伏応力の低下を定量的に予測できる可能性が示された．以上のことにより，本研究の成果は燃料電池自動車や風力発電の安全に貢献する．